In order to improve the aerodynamics of wings, tail units, control surfaces or flaps of aircraft and other flight equipment, increasingly so-called variable-shape wings are used. The aim is to change the profile curvature without there being any discontinuities such as flap gaps or kinks in the wing contour. One example of such a variable-shape wing structure is described in DE 100 55 961 A1 “Mechanismus zur zumindest bereichsweisen Verstellung der Wölbung von Tragflügeln”. A further example is provided by the test program “Advanced Fighter Technology Integration (AFTI)/F-11 Mission Adaptive Wing (MAW)” implemented in the USA. In this test program an aircraft was equipped with a variable-shape wing and was tested in flight.
Many such variable-shape wing concepts are associated with a common problem of finding a cover skin for the variable-shape wing, which cover skin may not only tolerate the deformations resulting from the variability in shape, but may also withstand the air loads that occur.
Within the context of the above-mentioned “Mission-Adaptive Wing” program, this problem was solved in that the top of the aerodynamic profile comprises a layer made of glass fiber reinforced polymer, and is elastically bent, while the bottom comprises several overlapping metal sheets which may slide one on top of the other during deformation of the wing. A further approach was presented in the lecture entitled “Formveränderung von Flügelstrukturen mittels integrierter Shape Memory Alloy Aktuatoren” within the context of the 1994 annual conference of the DGLR, where fiber reinforcement with an extremely anisotropic layer construction in an elastic matrix was discussed. Another approach was proposed by Boeing. Their “Flex Skin” concept comprises short straight strips of carbon fiber-reinforced polymer, where strips are embedded in an elastic matrix such as they are insulated from each other. This hybrid structure may be bent, but due to its strip geometry is rigid in a longitudinal direction.